1. Field of Invention
The present invention relates to electronic circuits, electro-optical devices, methods of driving electro-optical devices, and electronic apparatus.
2. Description of Related Art
Recently, interest has arisen in electro-optical devices including organic EL elements. In an electro-optical device of this type, analog gray scale is used as driving method to control halftones of organic EL elements (See e.g., Japanese Unexamined Patent Application Publication No. 2001-147659.). In a method of analog gray scale, a voltage between the source and gate of a driving transistor to supply a current of a current level in accordance with a multi-value data current to an organic EL element is used as a threshold voltage of the driving transistor. According to the method, a current supplied from a DA converter circuit in accordance with a luminance level (data current) is accumulated in a hold capacitor of a pixel circuit. A charge voltage corresponding to the amount of charge accumulated in the hold capacitor is applied to the gate of the driving transistor implemented by a thin-film transistor (TFT). The driving transistor supplies a driving current in accordance with the charge voltage corresponding to the data current to the organic EL element.
In the DA converter circuit that is used in the related art programming method or the like, implementation by thin-film transistors (TFTs) as adopted for the pixel circuit has been difficult due to a problem of precision, so that it has been common to use an external IC driver.
However, a DA converter circuit that is implemented by an external IC driver has had a problem that power consumption is larger compared with a TFT driver circuit that is formed on a display panel.
The present invention has been made in order to address the problem described above and provides an electronic circuit, an electro-optical device, a method of driving an electro-optical device, and an electronic apparatus that allows low power consumption and adequate display quality to be achieved simultaneously.